Single-receiver doppler-based sound source localization to track underwater target

Abstract

A system, method, and computer readable medium having a tracked package with a source emitting signals through an underwater environment that are detected by a receiver on a tracker and thereby producing a received signal, the tracker also having a controller and a position mechanism. The controller is configured to produce a sample from the received signal, receive velocity data from the position mechanism, and determine an angle relative to the source by comparing the received signal's frequency from a known source frequency and the velocity data.

What is claimed is: 
     
       1. A combination of a vessel and a non-transient computer readable medium containing program instructions for causing a computer in the vessel to perform a method, the method comprising:
 selecting a vessel configured to move on water and/or underwater, the vessel having the computer with the computer readable medium, having a propulsor capable of providing a motive force to move the vessel at a velocity on water and/or underwater, and having a receiver with a single hydrophone; 
 receiving, from the receiver, over time a plurality of samples n, each sample of said plurality of samples having a received frequency f r  and originating from a selected source emitting signals into an underwater environment, said signals having a source frequency f s ; 
 generating a first vessel velocity magnitude |v r |; 
 forming a virtual array with a first sample and a second sample of said plurality of samples n, said first sample having a first received frequency and said second sample having a second received frequency; and 
 determining a relative angle to said source from said receiver using said source frequency f s , said virtual array including said first received frequency and said second received frequency, and said first vessel velocity magnitude |v r | to provide an estimate of location of the selected source in the underwater environment. 
 
     
     
       2. The non-transient computer readable medium in the combination of  claim 1  wherein said plurality of samples n are received from only the single hydrophone in the receiver. 
     
     
       3. The non-transient computer readable medium in the combination of  claim 1  wherein said first vessel velocity magnitude |v r | is determined by a position module. 
     
     
       4. The non-transient computer readable medium in the combination of  claim 1  wherein said first vessel velocity magnitude |v r | is determined by an underwater positioner. 
     
     
       5. The non-transient computer readable medium in the combination of  claim 1 , wherein said plurality of samples n are assumed to have a constant waveform ping with said source frequency f s , and a constant pulse duration τ, and said determining said relative angle further uses said constant waveform ping and said constant pulse duration. 
     
     
       6. The non-transient computer readable medium in the combination of  claim 5 , wherein said receiver receives said plurality of samples n at a sampling rate of F s . 
     
     
       7. The non-transient computer readable medium in the combination of  claim 6 , wherein said first vessel velocity magnitude |v r | is not zero. 
     
     
       8. The non-transient computer readable medium in the combination of  claim 6 , further comprising the steps of:
 generating a second vessel velocity magnitude |v r |. 
 
     
     
       9. The non-transient computer readable medium in the combination of  claim 8  further comprising the steps of:
 calculating a time phase shift from the time difference between the sampling time of said first and said second sample of said plurality of samples n; 
 calculating a distance phase shift from the position difference between said first vessel velocity magnitude |v r | and said second vessel velocity magnitude |v r |; and 
 wherein said determining said relative angle further includes beamforming said time phase shift and said distance phase shift. 
 
     
     
       10. The non-transient computer readable medium in the combination of  claim 9 , wherein said beamforming produces a maximum beampattern θ s  that corresponds to the direction of incidence θ rel . 
     
     
       11. A system of Doppler-based relative angle resolution to track a selected package, the system comprising:
 a tracked package including a source configured to produce signals capable of traveling through an underwater environment Env, said signals having a source frequency f s ; 
 a tracker including a vessel configured to move on water and/or underwater, the vessel having a propulsor capable of providing a motive force to move the vessel at a velocity on water and/or underwater, having a receiver with a single hydrophone, having a position module and having a controller connected to the receiver; 
 wherein said receiver is configured to receive said signals and produce a plurality of samples n, each sample of said plurality of samples having a received frequency f r ; 
 wherein said tracker has a first vessel velocity magnitude |v r | that is generated by one of said position module and said controller; 
 wherein said controller is configured form a virtual array with a first sample and a second sample of said plurality of samples n, said first sample having a first received frequency and said second sample having a second received frequency; and 
 wherein said controller is further configured to determine a relative angle to said source from said receiver using said virtual array including said first received frequency and said second received frequency, said source frequency f s , and said first vessel velocity magnitude |v r | to provide an estimate of location of the tracked package in the underwater environment. 
 
     
     
       12. The system of Doppler-based relative angle resolution of  claim 11 , wherein said source produces signals having a constant waveform ping with said known signal source frequency f s , and a constant pulse duration τ. 
     
     
       13. The system of Doppler-based relative angle resolution of  claim 11 , wherein said first vessel velocity magnitude |v r | is not zero. 
     
     
       14. The system of Doppler-based relative angle resolution of  claim 13 , wherein said controller is further configured to receive a second vessel velocity magnitude |v r |, to calculate a time phase shift from the time difference between the sampling time of said first sample and said second sample of said plurality of samples, and to calculate a distance phase shift from the position difference between said first vessel velocity magnitude and said second vessel velocity magnitude; and wherein said controller's configuration to determine said relative angle further includes beamforming said time phase shift and said distance phase shift. 
     
     
       15. The system of Doppler-based relative angle resolution of  claim 14 , wherein said beamforming produces a maximum beampattern θ s  that corresponds to the direction of incidence θ rel . 
     
     
       16. A method of Doppler-based relative angle resolution to track a selected source, the method comprising the steps of:
 selecting a tracked package including a source configured to produce signals having a source frequency f s  capable of traveling through an underwater environment Env; 
 selecting a tracker including a vessel configured to move on water and/or underwater, the vessel having a propulsor capable of providing a motive force to move the vessel at a velocity on water and/or underwater, having a receiver with a single hydrophone, having a position module and having a controller connected to the receiver, wherein said receiver is configured to receive signals traveling through the underwater environment Env, wherein said tracker has a first vessel velocity magnitude |v r | that is generated by one of said position module and said controller; 
 receiving, with said receiver, said signals, thereby producing a first sample having a first received frequency f r  and a second sample having a second received frequency f r ; 
 generating said first vessel velocity magnitude |v r |; 
 forming a virtual array with said first sample and said second sample; and 
 determining a relative angle to said source from said receiver using said signal source frequency f s , said virtual array including said first received frequency and said second received frequency, and said first vessel velocity magnitude |v r | to provide an estimate of location of the selected source in the underwater environment. 
 
     
     
       17. The method of Doppler-based relative angle resolution of  claim 16  wherein said first vessel velocity magnitude is not zero and the method further includes the step of receiving a second vessel velocity magnitude |v r |. 
     
     
       18. The method of Doppler-based relative angle resolution of  claim 17  wherein said position module generates and sends said first vessel velocity magnitude and said second vessel velocity magnitude |v r | to said controller. 
     
     
       19. The method of Doppler-based relative angle resolution of  claim 17  further comprising the steps of:
 calculating, with said controller, a time phase shift from the time difference between the sampling time of said first sample and said second sample of said plurality of samples n; 
 calculating, with said controller, a distance phase shift from the position difference between said first vessel velocity magnitude |v r | and said second vessel velocity magnitude |v r |; and 
 wherein said determining said relative angle further includes beamforming said time phase shift and said distance phase shift. 
 
     
     
       20. The combination of  claim 1  wherein the vessel is one of an autonomous underwater vehicle or an autonomous surface vehicle.